Slave Making Ants
Biology 342 Fall 2010
By Zina Jenny and Joseph Perry
Imagine you are peacefully watching an ant colony you found on your lunch break.
As you sip your lemonade, watching the little black forms scurry about their day, you notice a single different kind of ant emerge from a crack in the sidewalk. He skirts around the colony and then returns to the crack, out of sight. Paying it no mind, you turn back towards a group of little black ants struggling to take apart a French fry.
Suddenly, out of nowhere, another mass of ants appears and begins to attack the colony! The workers attempt to put up a defense but the newcomers have much larger mandibles and easily crush all resistance. Victorious, they march into the resident colony and emerge some minutes later with small white forms clenched in their maws.
Wondering what the white forms are and what kind of ant this vicious band of marauders is, you manage to follow them back to their own hive. It turns out to be in a rotting stump a fair distance away. You watch the ants march into their hive, still triumphantly clinging to their prizes.
As you reflect on the events that have just transpired, you suddenly notice a number of small black ants of the first species nearby. "Run, flee!" you warn them, "These guys will tear you apart! Revenge isn't worth it!" But to your horror, they move confidently towards the thieve's hive- and begin cleaning it! The larger ants ignore them. At one point, you even see one of the smaller ants feeding a larger ant, regurgitating food right into those vicious mandibles which so recently tore their own cousins apart.
What you just witnessed is a raid by the species of ant called Polyergus breviceps, one of the thirty-five observed slave making ant species around the world (2. Wilson, E.O. 1975).
This behavior has developed independently at least six times. There are two distinct methods that slave making ants use to take over a colony (1. Slave Making Ants Taking Over a Colony). They will abduct larvae of other species and raise them to be workers, or take over an existing colony, replacing the old queen with one of their own (13. Foitzik, C. 2001). Enslaved ants will carry on as normal, unaware that anything is amiss. They are genetically encoded to carry out their duties of nest maintenance, larvae rearing and foraging given certain pheromonal cues. The slave making species is able to provide enough of these cues that the slaves cannot tell them apart from their own nest-mates.